Ni-based single crystal superalloy

ABSTRACT

The object of the present invention is to provide an Ni-based single crystal super alloy capable of improving strength by preventing precipitation of a TCP phase at high temperatures. This object is achieved by an Ni-based single crystal super alloy having a composition comprising 5.0-7.0 wt % of Al, 4.0-10.0 wt % of Ta, 1.1-4.5 wt % of Mo, 4.0-10.0 wt % of W, 3.1-8.0 wt % of Re, 0-0.50 wt % of Hf, 2.0-5.0 wt % of Cr, 0-9.9 wt % of Co and 4.1-14.0 wt % of Ru in terms of its weight ratio, with the remainder consisting of Ni and unavoidable impurities.

TECHNICAL FIELD

The present invention relates to a Ni-based single crystal super alloy,and more particularly, to a technology employed for improving the creepcharacteristics of Ni-based single crystal super alloy.

BACKGROUND ART

An example of the typical composition of Ni-based single crystal superalloy developed for use as a material for moving and stationary bladessubject to high temperatures such as those in aircraft and gas turbinesis shown in Table 1. TABLE 1 Alloy Elements (wt %) name Al Ti Ta Nb Mo WRe C Zr Hf Cr Co Ru Ni CMSX-2 6.0 1.0 6.0 — 1.0 8.0 — — — — 8.0 5.0 —Rem CMSX-4 5.6 1.0 6.5 — 0.6 6.0 3.0 — — — 6.5 9.0 — Rem RenéN6 6.0 —7.0 0.3 1.0 6.0 5.0 — — 0.2 4.0 13.0 — Rem CMSX-10K 5.7 0.3 8.4 0.1 0.45.5 6.3 — — 0.03 2.3 3.3 — Rem 3B 5.7 0.5 8.0 — — 5.5 6.0 0.05 — 0.155.0 12.5 3.0 Rem

In the above-mentioned Ni-based single crystal super alloys, afterperforming solution treatment at a prescribed temperature, agingtreatment is performed to obtain an Ni-based single crystal super alloy.This alloy is referred to as a so-called precipitation hardened alloy,and has a from in which the precipitation phase in the form of a γ′phase is precipitated in a matrix in the form of a γ phase.

Among the alloys listed in Table 1, CMSX-2 (Cannon-Muskegon, U.S. Pat.No. 4,582,548) is a first-generation alloy, CMSX-4 (Cannon-Muskegon,U.S. Pat. No. 4,643,782) is a second-generation alloy, RenéN6 (GeneralElectric, U.S. Pat. No. 5,455,120) and CMSX-10K (Canon-Muskegon, U.S.Pat. No. 5,366,695) are third-generation alloys, and 3B (GeneralElectric, U.S. Pat. No. 5,151,249) is a fourth-generation alloy.

Although the above-mentioned CMSX-2, which is a first-generation alloy,and CMSX-4, which is a second-generation alloy, have comparable creepstrength at low temperatures, since a large amount of the eutectic γ′phase remains following high-temperature solution treatment, their creepstrength is inferior to third-generation alloys.

In addition, although the third-generation alloys of RenéN6 and CMSX-10are alloys designed to have improved creep strength at high temperaturesin comparison with second-generation alloys, since the composite ratioof Re (5 wt % or more) exceeds the amount of Re that dissolves into thematrix (γ phase), the excess Re compounds with other elements and as aresult, a so-called TCP (topologically close packed) phase precipitatesat high temperatures causing the problem of decreased creep strength.

In addition, making the lattice constant of the precipitation phase (γ′phase) slightly smaller than the lattice constant of the matrix (γphase) is effective in improving the creep strength of Ni-based singlecrystal super alloys. However, since the lattice constant of each phasefluctuates greatly fluctuated according to the composite ratios of thecomposite elements of the alloy, it is difficult to make fineadjustments in the lattice constant and as a result, there is theproblem of considerable difficulty in improving creep strength.

In consideration of the above circumstances, the object of the presentinvention is to provide a Ni-based single crystal super alloy that makesit possible to improve strength by preventing precipitation of the TCPphase at high temperatures.

DISCLOSURE OF INVENTION

The following constitution is employed in the present invention in orderto achieve the above object.

The Ni-based single crystal super alloy of the present invention ischaracterized by having a composition comprising 5.0-7.0 wt % of Al,4.0-10.0 wt % of Ta, 1.1-4.5 wt % of Mo, 4.0-10.0 wt % of W, 3.1-8.0 wt% of Re, 0-0.50 wt % of Hf, 2.0-5.0 wt % of Cr, 0-9.9 wt % of Co and4.1-14.0 wt % of Ru in terms of its weight ratio, with the remainderconsisting of Ni and unavoidable impurities.

In addition, the Ni-based single crystal super alloy of the presentinvention is characterized by having a composition comprising 5.0-7.0 wt% of Al, 4.0-6.0 wt % of Ta, 1.1-4.5 wt % of Mo, 4.0-10.0 wt % of W,3.1-8.0 wt % of Re, 0-0.50 wt % of Hf, 2.0-5.0 wt % of Cr, 0-9.9 wt % ofCo, and 4.1-14.0 wt % of Ru in terms of weight ratio, with the remainderconsisting of Ni and unavoidable impurities.

In addition, the Ni-based single crystal super alloy of the presentinvention is characterized by having a composition comprising 5.0-7.0 wt% of Al, 4.0-6.0 wt % of Ta, 2.9-4.5 wt % of Mo, 4.0-10.0 wt % of W,3.1-8.0 wt % of Re, 0-0.50 wt % of Hf, 2.0-5.0 wt % of Cr, 0-9.9 wt % ofCo and 4.1-14.0 wt % of Ru in terms of weight ratio, with the remainderconsisting of Ni and unavoidable impurities.

According to the above Ni-based single crystal super alloy,precipitation of the TCP phase, which causes a decrease in creepstrength, during use at high temperatures is inhibited by the additionof Ru. In addition, by setting the composite ratios of other compositeelements within their optimum ranges, the lattice constant of the matrix(γ phase) and the lattice constant of the precipitation phase (γ′ phase)can be made to have optimum values. Consequently, strength at hightemperatures can be enhanced. Furthermore, since the composition of Ruis 4.1-14.0 wt %, precipitation of the TCP phase, which causes adecrease in creep strength, during use at high temperatures, isinhibited.

In addition, the Ni-based single crystal super alloy of the presentinvention is preferably having a composition comprising 5.9 wt % of Al,5.9 wt % of Ta, 3.9 wt % of Mo, 5.9 wt % of W, 4.9 wt % of Re, 0.10 wt %of Hf, 2.9 wt % of Cr, 5.9 wt % of Co and 5.0 wt % of Ru in terms ofweight ratio, with the remainder consisting of Ni and unavoidableimpurities, in the Ni-based single crystal super alloys previouslydescribed.

According to an Ni-based single crystal super alloy having thiscomposition, the creep endurance temperature at 137 MPa and 1000 hourscan be made to be 1344 K (1071° C.).

In addition, the Ni-based single crystal super alloy of the presentinvention is preferably having a composition comprising 5.8 wt % of Co,2.9 wt % of Cr, 3.1 wt % of Mo, 5.8 wt % of W, 5.8 wt % of Al, 5.6 wt %of Ta, 5.0 wt % of Ru, 4.9 wt % of Re and 0.10 wt % of Hf in terms ofweight ratio, with the remainder consisting of Ni and unavoidableimpurities, in the Ni-based single crystal super alloys previouslydescribed.

According to an Ni-based single crystal super alloy having thiscomposition, the creep endurance temperature at 137 MPa and 1000 hourscan be made to be 1366 K (1093° C.).

In addition, the Ni-based single crystal super alloy of the presentinvention is preferably having a composition comprising 5.8 wt % of Co,2.9 wt % of Cr, 3.9 wt % of Mo, 5.8 wt % of W, 5.8 wt % of Al, 5.8 wt %(5.82 wt %) or 5.6 wt % of Ta, 6.0 wt % of Ru, 4.9 wt % of, Re and 0.10wt % of Hf in terms of weight ratio, with the remainder consisting of Niand unavoidable impurities, in the Ni-based single crystal super alloyspreviously described.

According to an Ni-based single crustal super alloy having thiscomposition, the creep endurance temperature at 137 MPa and 1000 hourscan be made to be 1375 K (1102° C.) or 1379 K (1106° C.).

Furthermore, 0-2.0 wt % of Ti in terms of weight ratio can be includedin the Ni-based single crystal super alloys previously described.

Furthermore, 0-4.0 wt % of Nb in terms of weight ratio can be includedin the Ni-based single crystal alloys previously described.

Furthermore, at least one of elements selected from B, C, Si, Y, La, Ce,V and Zr can be included in the Ni-based single crystal super alloyspreviously described.

In this case, it is preferable that 0.05 wt % or less of B, 0.15 wt % orless of C, 0.1 wt % or less of Si, 0.1 wt % or less of Y, 0.1 wt % orless of La, 0.1 wt % or less of Ce, 1 wt % or less of V and 0.1 wt % orless of Zr in terms of weight ratio are included in the alloys.

Furthermore, the above described Ni-based single crystal super alloy ismore preferably having a composition comprising 5.0-7.0 wt % of Al,4.0-10.0 wt % of Ta, 1.1-4.5 wt % of Mo, 4.0-10.0 wt % of W, 3.1-8.0 wt% of Re, 0-0.50 wt % of Hf, 2.0-5.0 wt % of Cr, 0-9.9 wt % of Co,10.0-14.0 wt % of Ru, 4.0 wt % or less of Nb, 2.0 wt % or less of Ti,0.05 wt % or less of B, 0.15 wt % or less of C, 0.1 wt % or less of Si,0.1 wt % or less of Y, 0.1 wt % or less of La, 0.1 wt % or less of Ce, 1wt % or less of V and 0.1 wt % or less of Zr.

Furthermore, the above described Ni-based single crystal super alloy ismore preferably having a composition comprising 5.8-7.0 wt % of Al,4.0-5.6 wt % of Ta, 3.3-4.5 wt % of Mo, 4.0-10.0 wt % of W, 3.1-8.0 wt %of Re, 0-0.50 wt % of Hf, 2.9-4.3 wt % of Cr, 0-9.9 wt % of Co, 4.1-14.0wt % of Ru, 4.0 wt % or less of Nb, 2.0 wt % or less of Ti, 0.05 wt % orless of B, 0.15 wt % or less of C, 0.1 wt % or less of Si, 0.1 wt % orless of Y, 0.1 wt % or less of La, 0.1 wt % or less of Ce, 1 wt % orless of V and 0.1 wt % or less of Zr.

Furthermore, the above described Ni-based single crystal super alloy ismore preferably having a composition comprising 5.0-7.0 wt % of Al,4.0-10.0 wt % of Ta, 1.1-4.5 wt % of Mo, 4.0-10.0 wt % of W, 3.1-8.0 wt% of Re, 0-0.50 wt % of Hf, 2.9-5.0 wt % of Cr, 0-9.9 wt % of Co,6.5-14.0 wt % of Ru, 4.0 wt % or less of Nb, 2.0 wt % or less of Ti,0.05 wt % or less of B, 0.15 wt % or less of C, 0.1 wt % or less of Si,0.1 wt % or less of Y, 0.1 wt % or less of La, 0.1 wt % or less of Ce, 1wt % or less of V and 0.1 wt % or less of Zr.

Furthermore, the above described Ni-based single crystal super alloy ismore preferably having a composition comprising 5.0-7.0 wt % of Al,4.0-6.0 wt % of Ta, 3.3-4.5 wt % of Mo, 4.0-10.0 wt % of W, 3.1-8.0 wt %of Re, 0-0.50 wt % of Hf, 2.0-5.0 wt % of Cr, 0-9.9 wt % of Co, 4.1-14.0wt % of Ru, 4.0 wt % or less of Nb, 2.0 wt % or less of Ti, 0.05 wt % orless of B, 0.15 wt % or less of C, 0.1 wt % or less of Si, 0.1 wt % orless of Y, 0.1 wt % or less of La, 0.1 wt % or less of Ce, 1 wt % orless of V and 0.1 wt % or less of Zr.

Furthermore, the above described Ni-based single crystal super alloy ismore preferably having a composition comprising 5.0-7.0 wt % of Al,4.0-5.6 wt % of Ta, 3.3-4.5 wt % of Mo, 4.0-10.0 wt % of W, 3.1-8.0 wt %of Re, 0-0.50 wt % of Hf, 2.0-5.0 wt % of Cr, 0-9.9 wt % of Co, 4.1-14.0wt % of Ru, 4.0 wt % or less of Nb, 2.0 wt % or less of Ti, 0.05 wt % orless of B, 0.15 wt % or less of C, 0.1 wt % or less of Si, 0.1 wt % orless of Y, 0.1 wt % or less of La, 0.1 wt % or less of Ce, 1 wt % orless of V and 0.1 wt % or less of Zr.

Furthermore, the above described Ni-based single crystal super alloy ismore preferably having a composition comprising 5.0-7.0 wt % of Al,4.0-10.0 wt % of Ta, 3.1-4.5 wt % of Mo, 4.0-10.0 wt % of W, 3.1-8.0 wt% of Re, 0-0.50 wt % of Hf, 2.0-5.0 wt % of Cr, 0-9.9 wt % of Co,4.1-14.0 wt % of Ru, 4.0 wt % or less of Nb, 0.05 wt % or less of B,0.15 wt % or less of C, 0.1 wt % or less of Si, 0.1 wt % or less of Y,0.1 wt % or less of La, 0.1 wt % or less of Ce, 1 wt % or less of V and0.1 wt % or less of Zr.

Furthermore, the above described Ni-based single crystal super alloy ismore preferably having a composition comprising 5.8-7.0 wt % of Al,4.0-10.0 wt % of Ta, 3.1-4.5 wt % of Mo, 4.0-10.0 wt % of W, 3.1-8.0 wt% of Re, 0-0.50 wt % of Hf, 2.0-5.0 wt % of Cr, 0-9.9 wt % of Co,4.1-14.0 wt % of Ru, 4.0 wt % or less of Nb, 2.0 wt % or less of Ti,0.05 wt % or less of B, 0.15 wt % or less of C, 0.1 wt % or less of Si,0.1 wt % or less of Y, 0.1 wt % or less of La, 0.1 wt % or less of Ce, 1wt % or less of V and 0.1 wt % or less of Zr.

Furthermore, the above described Ni-based single crystal super alloy ismore preferably having a composition comprising 5.0-7.0 wt % of Al,4.0-10.0 wt % of Ta, 3.1-4.5 wt % of Mo, 4.0-10.0 wt % of W, 3.1-8.0 wt% of Re, 0-0.50 wt % of Hf, 2.9-4.3 wt % of Cr, 0-9.9 wt % of Co,4.1-14.0 wt % of Ru, 4.0 wt % or less of Nb, 2.0 wt % or less of Ti,0.05 wt % or less of B, 0.15 wt % or less of C, 0.1 wt % or less of Si,0.1 wt % or less of Y, 0.1 wt % or less of La, 0.1 wt % or less of Ce, 1wt % or less of V and 0.1 wt % or less of Zr.

In addition, the above described Ni-based single crystal super alloy ismore preferably having a composition comprising 5.0-7.0 wt % of Al,4.0-10.0 wt % of Ta+Nb+Ti, 3.3-4.5 wt % of Mo, 4.0-10.0 wt % of W,3.1-8.0 wt % of Re, 0-0.50 wt % of Hf, 2.0-5.0 wt % of Cr, 0-9.9 wt % ofCo, 4.1-14.0 wt % of Ru, 0.05 wt % or less of B, 0.15 wt % or less of C,0.1 wt % or less of Si, 0.1 wt % or less of Y, 0.1 wt % or less of La,0.1 wt % or less of Ce, 1 wt % or less of V and 0.1 wt % or less of Zr.

Moreover, the Ni-based single crystal super alloy of the presentinvention is characterized by a2≦0.999a1 when the lattice constant ofthe matrix is taken to be a1 and the lattice constant of theprecipitation phase is taken to be a2 in the Ni-based single crystalsuper alloys previously described.

According to this Ni-based single crystal super alloy, the relationshipbetween a1 and a2 is such that a2≦0.999a1 when the lattice constant ofthe matrix is taken to be a1 and the lattice constant of theprecipitation phase is taken to be a2, and since the lattice constant a2of the precipitation phase is −0.1% or less of the lattice constant a1of the matrix, the precipitation phase that precipitates in the matrixprecipitates so as to extend continuously in the direction perpendicularto the direction of the load. As a result, strength at high temperaturescan be enhanced without dislocation defects moving within the alloystructure under stress.

In this case, it is more preferable that the lattice constant of thecrystals of the precipitation phase a2 is 0.9965 or less of the latticeconstant of the crystals of the matrix a1

Furthermore, the Ni-based single crystal super alloy of the presentinvention is characterized by comprising the feature that thedislocation space of the alloy is 40 nm or less.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram showing a relationship between change of latticemisfit of the alloy and creep rupture life of the alloy.

FIG. 2 is a diagram showing a relationship between dislocation space ofthe alloy and creep rupture life of the alloy.

FIG. 3 is a transmission electron microgram of the Ni-based singlecrystal super alloy showing an embodiment of the dislocation networksand dislocation space of the Ni-based single crystal super alloy of thepresent invention.

BEST MODE FOR CARRYING OUT THE INVENTION

The following provides a detailed explanation for carrying out thepresent invention.

The Ni-based single crystal super alloy of the present invention is analloy comprised of Al, Ta, Mo, W, Re, Hf, Cr, Co, Ru, Ni (remainder) andunavoidable impurities.

The above Ni-based single crystal super alloy is an alloy having acomposition comprising 5.0-7.0 wt % of Al, 4.0-10.0 wt % of Ta, 1.1-4.5wt % of Mo, 4.0-10.0 wt % of W, 3.1-8.0 wt % of Re, 0-0.50 wt % of Hf,2.0-5.0 wt % of Cr, 0-9.9 wt % of Co and 4.1-14.0 wt % of Ru, with theremainder consisting of Ni and unavoidable impurities.

In addition, the above Ni-based single crystal super alloy is an alloyhaving a composition comprising 5.0-7.0 wt % of Al, 4.0-6.0 wt % of Ta,1.1-4.5 wt % of Mo, 4.0-10.0 wt % of W, 3.1-8.0 wt % of Re, 0-0.50 wt %of Hf, 2.0-5.0 wt % of Cr, 0-9.9 wt % of Co and 4.1-14.0 wt % of Ru,with the remainder consisting of Ni and unavoidable impurities.

Moreover, the above Ni-based single crystal super alloy is an alloyhaving a composition comprising 5.0-7.0 wt % of Al, 4.0-6.0 wt % of Ta,2.9-4.5 wt % of Mo, 4.0-10.0 wt % of W, 3.1-8.0 wt % of Re, 0-0.50 wt %of Hf, 2.0-5.0 wt % of Cr, 0-9.9 wt % of Co and 4.1-14.0 wt % of Ru,with the remainder consisting of Ni and unavoidable impurities.

All of the above alloys have an austenite phase in the form of a γ phase(matrix) and an intermediate regular phase in the form of a γ′ phase(precipitation phase) that is dispersed and precipitated in the matrix.The γ′ phase is mainly composed of an intermetallic compound representedby Ni₃Al, and the strength of the Ni-based single crystal super alloy athigh temperatures is improved by this γ′ phase.

Cr is an element that has superior oxidation resistance and improves thehigh-temperature corrosion resistance of the Ni-based single crystalsuper alloy. The composite ratio of Cr is preferably within the range of2.0 wt % or more to 5.0 wt % or less, and more preferably 2.9 wt %. Thisratio is more preferably within the range of 2.9 wt % or more to 5.0 wt% or less, more preferably within the range of 2.9 wt % or more to 4.3wt % or less, and most preferably 2.9 wt %. If the composite ratio of Cris less than 2.0 wt %, the desired high-temperature corrosion resistancecannot be secured, thereby making this undesirable. If the compositeratio of Cr exceeds 5.0 wt %, in addition to precipitation of the γ′phase being inhibited, harmful phases such as a σ phase or μ phase formthat cause a decrease in strength at high temperatures, thereby makingthis undesirable.

In addition to improving strength at high temperatures by dissolvinginto the matrix in the form of the γ phase in the presence of W and Ta,Mo also improves strength at high temperatures due to precipitationhardening. Furthermore, Mo also improves the aftermentioned latticemisfit and dislocation networks of the alloy which relatecharacteristics of this alloy.

The composite ratio of Mo is preferably within the range of 1.1 wt % ormore to 4.5 wt % or less, more preferably within the range of 2.9 wt %or more to 4.5 wt % or less. This ratio is more preferably within therange of 3.1 wt % or more to 4.5 wt % or less, more preferably withinthe range of 3.3 wt % or more to 4.5 wt % or less, and most preferably3.1 wt % or 3.9 wt %. If the composite ratio of Mo is less than 1.1 wt%, strength at high temperatures cannot be maintained at the desiredlevel, thereby making this undesirable. If the composite ratio of Moexceeds 4.5 wt %, strength at high temperatures decreases, and corrosionresistance at high temperatures also decreases, thereby making thisundesirable.

W improves strength at high temperatures due to the actions of solutionhardening and precipitation hardening in the presence of Mo and Ta aspreviously mentioned. The composite ratio of W is preferably within therange of 4.0 wt % or more to 10.0 wt % or less, and most preferably 5.9wt % or 5.8 wt %. If the composite ratio of W is less than 4.0 wt %,strength at high temperatures cannot be maintained at the desired level,thereby making this undesirable. If the composite ratio of W exceeds10.0 wt %, high-temperature corrosion resistance decreases, therebymaking this undesirable.

Ta improves strength at high temperatures due to the actions of solutionhardening and precipitation hardening in the presence of Mo and W aspreviously mentioned, and also improves strength at high temperatures asa result of a portion of the Ta undergoing precipitation hardeningrelative to the γ′ phase. The composite ratio of Ta is preferably withinthe range of 4.0 wt % or more to 10.0 wt % or less, more preferablywithin the range of 4.0 wt % or more to 6.0 wt % or less. This ratio ismore preferably within the range of 4.0 wt % or more to 5.6 wt % orless, and most preferably 5.6 wt % or 5.82 wt %. If the composite ratioof Ta is less than 4.0 wt %, strength at high temperatures cannot bemaintained at the desired level, thereby making this undesirable. If thecomposite ratio of Ta exceeds 10.0 wt %, the σ phase and μ phase formthat cause a decrease in strength at high temperatures, thereby makingthis undesirable.

Al improves strength at high temperatures by compounding with Ni to forman intermetallic compound represented by Ni₃Al, which composes the γ′phase that finely and uniformly disperses and precipitates in thematrix, at a ratio of 60-70% in terms of volume percent. The compositeratio of Al is preferably within the range of 5.0 wt % or more to 7.0 wt% or less. This ratio is more preferably within the range of 5.8 wt % ormore to 7.0 wt % or less, and most preferably 5.9 wt % or 5.8 wt %. Ifthe composite ratio of Al is less than 5.0 wt %, the precipitated amountof the γ′ phase becomes insufficient, and strength at high temperaturescannot be maintained at the desired level, thereby making thisundesirable. If the composite ratio of Al exceeds 7.0 wt %, a largeamount of a coarse γ phase referred to as the eutectic γ′ phase isformed, and this eutectic γ′ phase prevents solution treatment and makesit impossible to maintain strength at high temperatures at a high level,thereby making this undesirable.

Hf is an element that segregates at the grain boundary and improvesstrength at high temperatures by strengthening the grain boundary as aresult of being segregated at the grain boundary between the γ phase andthe γ′ phase. The composite ratio of Hf is preferably within the rangeof 0.01 wt % or more to 0.50 wt % or less, and most preferably 0.10 wt%. If the composite ratio of Hf is less than 0.01 wt %, the precipitatedamount of the γ′ phase becomes insufficient and strength at hightemperatures cannot be maintained at the desired level, thereby makingthis undesirable. However, the composite ratio of Hf may be within therange of 0 wt % or more to less than 0.01 wt %, if necessary.Furthermore, if the composite ratio of Hf exceeds 0.50 wt %, localmelting is induced which results in the risk of decreased strength athigh temperatures, thereby making this undesirable.

Co improves strength at high temperatures by increasing the solutionlimit at high temperatures relative to the matrix such as Al and Ta, anddispersing and precipitating a fine γ′ phase by heat treatment. Thecomposite ratio of Co is preferably within the range of 0.1 wt % or moreto 9.9 wt % or less, and most preferably 5.8 wt %. If the compositeratio of Co is less than 0.1 wt %, the precipitated amount of the γ′phase becomes insufficient and the strength at high temperatures cannotbe maintained, thereby making this undesirable. However, the compositeratio of Co may be within the range of 0 wt % or more to less than 0.1wt %, if necessary. Furthermore, if the composite ratio of Co exceeds9.9 wt %, the balance with other elements such as Al, Ta, Mo, W, Hf andCr is disturbed resulting in the precipitation of harmful phases thatcause a decrease in strength at high temperatures, thereby making thisundesirable.

Re improves strength at high temperatures due to solution strengtheningas a result of dissolving in the matrix in the form of the γ phase. Onthe other hand, if a large amount of Re is added, the harmful TCP phaseprecipitates at high temperatures, resulting in the risk of decreasedstrength at high temperatures. Thus, the composite ratio of Re ispreferably within the range of 3.1 wt % or more to 8.0 wt % or less, andmost preferably 4.9 wt %. If the composite ratio of Re is less than 3.1wt %, solution strengthening of the γ phase becomes insufficient andstrength at high temperatures cannot be maintained at the desired level,thereby making this undesirable. If the composite ratio of Re exceeds8.0 wt %, the TCP phase precipitates at high temperatures and strengthat high temperatures cannot be maintained at a high level, therebymaking this undesirable.

Ru improves strength at high temperatures by inhibiting precipitation ofthe TCP phase. The composite ratio of Ru is preferably within the rangeof 4.1 wt % or more to 14.0 wt % or less. This ratio is more preferablywithin the range of 10.0 wt % or more to 14.0 wt % or less, orpreferably within the range of 6.5 wt % or more to 14.0 wt % or less,and most preferably 5.0 wt %, 6.0 wt % or 7.0 wt %. If the compositeratio of Ru is less than 1.0 wt %, the TCP phase precipitates at hightemperatures and strength at high temperatures cannot be maintained at ahigh level, thereby making this undesirable. If the composite ratio ofRu is less than 4.1 wt %, strength at high temperatures decreasescompared to the case when the composite ratio of Ru is 4.1 wt % or more.Furthermore, if the composite ratio of Ru exceeds 14.0 wt %, the ε phaseprecipitates and strength at high temperatures decreases which is alsoundesirable.

Particularly in the present invention, by adjusting the composite ratiosof Al, Ta, Mo, W, Hf, Cr, Co and Ni to the optimum ratios, together withimproving strength at high temperatures by setting the aftermentionedlattice misfit and dislocation networks of the alloy which arecalculated from the lattice constant of the γ phase and the latticeconstant of the γ′ phase within their optimum ranges, and precipitationof the TCP phase can be inhibited by adding Ru. Furthermore, byadjusting the composite ratios of Al, Cr, Ta and Mo to theaforementioned ratios, the production cost for the alloy can bedecreased. In addition, relative strength of the alloy can be increasedand the lattice misfit and dislocation networks of the alloy can beadjusted to the optimum value.

In addition, in usage environments at high temperatures from 1273 K(1000° C.) to 1373K (1100° C.), when the lattice constant of thecrystals that compose the matrix in the form of the γ phase is taken tobe a1, and the lattice constant of the crystals that compose theprecipitation phase in the form of the γ′ phase is taken to be a2, thenthe relationship between a1 and a2 is preferably such that a2≦0.999a1.Namely, lattice constant a2 of the crystals of the precipitation phaseis preferably −0.1% or less lattice constant a1 of the crystals of thematrix. Furthermore, it is more preferable that the lattice constant ofthe crystals of the precipitation phase a2 is 0.9965 or less of thelattice constant of the crystals of the matrix a1. In this case, theabove-described relationship between a1 and a2 becomes a2≦0.9965a1. Inthe following descriptions, the percentage of the lattice constant a2relative to the lattice constant a1 is called “lattice misfit”.

In addition, in the case both of the lattice constants are in the aboverelationship, since the precipitation phase precipitates so as to extendcontinuously in the direction perpendicular to the direction of the loadwhen the precipitation phase precipitates in the matrix due to heattreatment, creep strength can be enhanced without movement ofdislocation defects in the alloy structure in the presence of stress.

In order to make the relationship between lattice constant a1 andlattice constant a2 such that a2≦0.999a1, the composition of thecomposite elements that compose the Ni-based single crystal super alloyis suitably adjusted.

FIG. 1 shows a relationship between the lattice misfit of the alloy andthe time until the alloy demonstrates creep rupture (creep rupturelife).

In FIG. 1, when the lattice misfit is approximately −0.35 or lower, thecreep rupture life is approximately higher than the required value (thevalue shown by a dotted line in a vertical axis of the figure).Therefore, in the present invention, the preferable value of the latticemisfit is determined to −0.35 or lower. In order to maintain the latticemisfit to −0.35 or lower, the composition of Mo is maintained to a highlevel, and the composition of the other composite elements is suitablyadjusted.

According to the above Ni-based super crystal super alloy, precipitationof the TCP phase, which causes decreased creep strength, during use athigh temperatures is inhibited by addition of Ru. In addition, bysetting the composite ratios of other composite elements to theiroptimum ranges, the lattice constant of the matrix (γ phase) and thelattice constant of the precipitation phase (γ′ phase) can be made tohave optimum values. As a result, creep strength at high temperaturescan be improved.

Ti can be further included in the above Ni-based super crystal superalloy. The composite ratio of Ta is preferably within the range of 0 wt% or more to 2.0 wt % or less. If the composite ratio of Ti exceeds 2.0wt %, the harmful phase precipitates and the strength at hightemperatures cannot be maintained, thereby making this undesirable.

Furthermore, Nb can be further included in the above Ni-based supercrystal super alloy. The composite ratio of Nb is preferably within therange of 0 wt % or more to 4.0 wt % or less. If the composite ratio ofNb exceeds 4.0 wt %, the harmful phase precipitates and the strength athigh temperatures cannot be maintained, thereby making this undesirable.

Alternatively, strength at high temperatures can be improved byadjusting the total composite ratio of Ta, Nb and Ti (Ta+Nb+Ti) withinthe range of 4.0 wt % or more to 10.0 wt % or less.

Furthermore, in addition to the unavoidable impurities, B, C, Si, Y, La,Ce, V and Zr and the like can be included in the above Ni-based supercrystal super alloy, for example. When the alloy includes at least oneof elements selected from B, C, Si, Y, La, Ce, V and Zr, the compositeratio of each element is preferably 0.05 wt % or less of B, 0.15 wt % orless of C, 0.1 wt % or less of Si, 0.1 wt % or less of Y, 0.1 wt % orless of La, 0.1 wt % or less of Ce, 1 wt % or less of V and 0.1 wt % orless of Zr. If the composite ratio of each element exceeds the aboverange, the harmful phase precipitates and the strength at hightemperatures cannot be maintained, thereby making this undesirable.

furthermore, in the above Ni-based single crystal super alloy, it ispreferable that a dislocation space of the alloy is 40 nm or less. Thereticulated dislocation (displacement of atoms which are connected as aline) in the alloy is called dislocation networks, and a space betweenadjacent reticulations is called “dislocation space”. FIG. 2 shows arelationship between the dislocation space of the alloy and the timeuntil the alloy demonstrates creep rupture (creep rupture life).

In FIG. 2, when the dislocation space is approximately 40 nm or lower,the creep rupture life is approximately higher than the required value(the value shown by a dotted line in a vertical axis of the figure).Therefore, in the present invention, the preferable value of thedislocation space is determined to 40 nm or lower. In order to maintainthe dislocation space to 40 nm or lower, the composition of Mo ismaintained to a high level, and the composition of the other compositeelements is suitably adjusted.

FIG. 3 is a transmission electron microgram of the Ni-based singlecrystal super alloy showing an embodiment (aftermentioned embodiment 3)of the dislocation networks and dislocation space of the Ni-based singlecrystal super alloy of the present invention. As shown in FIG. 3, incase of the Ni-based single crystal super alloy of the presentinvention, the dislocation space is 40 nm or lower.

In addition, some of the conventional Ni-based single crystal superalloys may cause reverse partitioning, however, in Ni-based singlecrystal super alloy of the present invention does not cause reversepartitioning.

EMBODIMENTS

The effect of the present invention is shown using followingembodiments.

Melts of various Ni-based single crystal super alloys were preparedusing a vacuum melting furnace, and alloy ingots were cast using thealloy melts. The composite ratio of each of the alloy ingots (referenceexamples 1-6, embodiments 1-14) is shown in Table 2. TABLE 2 Sample(alloy Elements (wt %) name) Al Ta Nb Mo W Re Hf Cr Co Ru Ni Reference6.0 5.8 3.2 6.0 5.0 0.1 3.0 6.0 2.0 Rem Example 1 Reference 5.9 5.7 3.25.9 5.0 0.1 3.0 5.9 3.0 Rem Example 2 Reference 6.0 6.0 4.0 6.0 5.0 0.13.0 6.0 3.0 Rem Example 3 Reference 5.9 5.9 4.0 5.9 5.0 0.1 3.0 5.9 4.0Rem Example 4 Reference 5.9 5.7 3.1 5.9 4.9 0.1 2.9 5.9 4.0 Rem Example5 Reference 5.7 5.7 2.9 7.7 4.8 0.1 2.9 5.7 3.0 Rem Example 6 Embodi-5.9 5.9 3.9 5.9 4.9 0.1 2.9 5.9 5.0 Rem ment 1 Embodi- 5.8 5.6 3.1 5.84.9 0.1 2.9 5.8 5.0 Rem ment 2 Embodi- 5.8 5.8 3.9 5.8 4.9 0.1 2.9 5.86.0 Rem ment 3 Embodi- 5.6 5.6 2.8 5.6 6.9 0.1 2.9 5.6 5.0 Rem ment 4Embodi- 5.6 5.0 0.5 2.8 5.6 6.9 0.1 2.9 5.6 5.0 Rem ment 5 Embodi- 5.65.6 1.0 2.8 5.6 4.7 0.1 2.9 5.6 5.0 Rem ment 6 Embodi- 5.8 5.6 3.9 5.84.9 0.1 2.9 5.8 6.0 Rem ment 7 Embodi- 5.7 5.5 1.0 3.8 5.7 4.8 0.1 2.85.5 5.9 Rem ment 8 Embodi- 5.8 5.6 3.1 6.0 5.0 0.1 2.9 5.8 4.6 Rem ment9 Embodi- 5.8 5.6 3.1 6.0 5.0 0.1 2.9 5.8 5.2 Rem ment 10 Embodi- 5.85.6 3.3 6.0 5.0 0.1 2.9 5.8 5.2 Rem ment 11 Embodi- 5.8 5.6 3.3 6.0 5.00.1 2.9 5.8 6.0 Rem ment 12 Embodi- 5.9 2.9 1.5 3.9 5.9 4.9 0.1 2.9 5.96.1 Rem ment 13 Embodi- 5.7 5.52 3.1 5.7 4.8 0.1 2.9 5.7 7.0 Rem ment 14

Next, solution treatment and aging treatment were performed on the alloyingots followed by observation of the state of the alloy structure witha scanning electron microscope (SEM). Solution treatment consisted ofholding for 1 hour at 1573K (1300° C.) followed by heating to 1613K(1340° C.) and holding for 5 hours. In addition, aging treatmentconsisted of consecutively performing primary aging treatment consistingof holding for 4 hours at 1273K-1423K (1000° C.-1150° C.) and secondaryaging treatment consisting of holding for 20 hours at 1143K (870° C.).

As a result, a TCP phase was unable to be confirmed in the structure ofeach sample.

Next, a creep test was performed on each sample that underwent solutiontreatment and aging treatment. The creep test consisted of measuring thetime until each sample (reference examples 1-6 and embodiments 1-14)demonstrated creep rupture as the sample life under each of thetemperature and stress conditions shown in Table 3. Furthermore, thevalue of the lattice misfit of each sample was also measured, and theresult thereof is disclosed in Table 3. In addition, the value of thelattice misfit of each of the conventional alloys shown in Table 1(comparative examples 1-5) was also measured, and the result thereof isdisclosed in Table 4. TABLE 3 Creep test conditions/ rupture life (h)1273 K 1373 K Sample (1000° C.) (1100° C.) Lattice (alloy name) 245 MPa137 MPa Misfit Reference Example 1 209.35 105.67 −0.39 Reference Example2 283.20 158.75 −0.40 Reference Example 3 219.37 135.85 −0.56 ReferenceExample 4 274.38 153.15 −0.58 Reference Example 5 328.00 487.75 −0.58Reference Example 6 203.15 −0.41 Embodiment 1 5.09.95 32.6.50 −0.60Embodiment 2 420.60 753.95 −0.42 Embodiment 3 1062.50 −0.62 Embodiment 4966.00 −0.44 Embodiment 5 1256.00 −0.48 Embodiment 6 400.00 −0.45Embodiment 7 1254.00 −0.60 Embodiment 8 682.00 −0.63 Embodiment 9 550.00−0.42 Embodiment 10 658.50 −0.45 Embodiment 11 622.00 −0.48 Embodiment12 683.50 −0.51 Embodiment 13 412.7 766.35 −0.62 Embodiment 14 1524.00−0.45

TABLE 4 Sample (alloy name) Lattice Misfit Comparative Example 1(CMSX-2) −0.36 Comparative Example 2 (CMSX-4) −0.14 Comparative Example3 (RenéN6) −0.22 Comparative Example 4 (CMSX-10K) −0.14 ComparativeExample 5 (3B) −0.25

As is clear from Table 3, the samples of the reference examples 1-6 andembodiments 1-14 were determined to have high strength even under hightemperature conditions of 1273K (1000° C.). In particular, referenceexample 5 having a composition of 4.0 wt % of Ru, embodiments 1, 2, 4,9, 10 and 11 having a composition approximately 5.0 wt % of Ru,embodiments 3, 12 and 13 having a composition of 6.0 wt % of Ru, andembodiment 14 having a composition of 7.0 wt % of Ru, were determined tohave high strength at high temperature.

Furthermore, as is clear from Tables 3 and 4, the lattice misfit ofcomparative examples were −0.35 and more, whereas those of referenceexamples 1-6 and embodiments 1-14 were −0.35 or less.

In addition, the creep rupture characteristics (withstand temperature)were compared for the alloys of the prior art shown in Table 1(Comparative Examples 1 through 5) and the sample shown in Table 2(reference examples 1-6 and embodiments 1-14). The result thereof isdisclosed in Table 5. Creep rupture characteristics were determinedeither as a result of measuring the temperature until the sampleruptured under conditions of applying stress of 137 MPa for 1000 hours,or converting the rupture temperature of the sample under thoseconditions. TABLE 5 Sample (alloy name) Withstand temperature (° C.)Reference Example 1 1315 K (1042° C.) Reference Example 2 1325 K (1052°C.) Reference Example 3 1321 K (1048° C.) Reference Example 4 1324 K(1051° C.) Reference Example 5 1354 K (1081° C.) Reference Example 61332 K (1059° C.) Embodiment 1 1344 K (1071° C.) Embodiment 2 1366 K(1093° C.) Embodiment 3 1375 K (1102° C.) Embodiment 4 1372 K (1099° C.)Embodiment 5 1379 K (1106° C.) Embodiment 6 1379 K (1106° C.) Embodiment7 1379 K (1106° C.) Embodiment 8 1363 K (1090° C.) Embodiment 9 1358 K(1085° C.) Embodiment 10 1362 K (1089° C.) Embodiment 11 1361 K (1088°C.) Embodiment 12 1363 K (1090° C.) Embodiment 13 1366 K (1093° C.)Embodiment 14 1384 K (1111° C.) Comparative Example 1 (CMSX-2) 1289 K(1016° C.) Comparative Example 2 (CMSX-4) 1306 K (1033° C.) ComparativeExample 3 (RenéN6) 1320 K (1047° C.) Comparative Example 4 (CMSX-10K)1345 K (1072° C.) Comparative Example 5 (3B) 1353 K (1080° C.)(Converted to 137 MPa, 1000 hours)

As is clear from Table 5, the samples of reference examples 1-6 andembodiments 1-14 were determined to have a high withstand temperature(1356K (1083° C.)) equal to or greater than the alloys of the prior art(comparative Examples 1-5). In particular, samples of reference examples1-6 and embodiments 1-14 were determined to have a high withstandtemperature (embodiment 1: 1344K (1071° C.), embodiment 2: 1366K (1093°C.), embodiment 3: 1375K (1102° C.), embodiment 4: 1372K (1099° C.),embodiment 5: 1379K (1106° C.), embodiment 6: 1379K (1106° C.),embodiment 7: 1379K (1106° C.), embodiment 8: 1363K (1090° C.),embodiment 9: 1358K (1085° C.), embodiment 10: 1362K (1089° C.),embodiment 11: 1361K (1088° C.), embodiment 12: 1363K (1090° C.),embodiment 13: 1366K (1093° C.) and embodiment 14: 1384K (1111° C.).

Thus, this alloy has a higher heat resistance temperature than Ni-basedsingle crystal super alloys of the prior art, and was determined to havehigh strength even at high temperatures.

Furthermore, in the Ni-based single crystal super alloy, if thecomposite ratio of Ru excessively increases, the ε phase precipitatesand strength at high temperatures deceases. Therefore, the compositeratio of Ru is preferably be determined to a range so as to keep thebalance against the composition of the other composite elements issuitably adjusted (4.1 wt % or more to 14.0 wt % or less, for example).

1. An Ni-based single crystal super alloy having a compositioncomprising 5.0-7.0 wt % of Al, 4.0-10.0 wt % of Ta, 1.1-4.5 wt % of Mo,4.0-10.0 wt % of W, 3.1-8.0 wt % of Re, 0-0.50 wt % of Hf, 2.0-5.0 wt %of Cr, 0-9.9 wt % of Co and 4.1-14.0 wt % of Ru in terms of its weightratio, with the remainder consisting of Ni and unavoidable impurities.2. An Ni-based single crystal super alloy having a compositioncomprising 5.0-7.0 wt % of Al, 4.0-6.0 wt % of Ta, 1.1-4.5 wt % of Mo,4.0-10.0 wt % of W, 3.1-8.0 wt % of Re, 0-0.50 wt % of Hf, 2.0-5.0 wt %of Cr, 0-9.9 wt % of Co, and 4.1-14.0 wt % of Ru in terms of weightratio, with the remainder consisting of Ni and unavoidable impurities.3. An Ni-based single crystal super alloy having a compositioncomprising 5.0-7.0 wt % of Al, 4.0-6.0 wt % of Ta, 2.9-4.5 wt % of Mo,4.0-10.0 wt % of W, 3.1-8.0 wt % of Re, 0-0.50 wt % of Hf, 2.0-5.0 wt %of Cr, 0-9.9 wt % of Co and 4.1-14.0 wt % of Ru in terms of weightratio, with the remainder consisting of Ni and unavoidable impurities.4. An Ni-based single crystal super alloy according to claim 1 having acomposition comprising 5.9 wt % of Al, 5.9 wt % of Ta, 3.9 wt % of Mo,5.9 wt % of W, 4.9 wt % of Re, 0.10 wt % of Hf, 2.9 wt % of Cr, 5.9 wt %of Co and 5.0 wt % of Ru in terms of weight ratio, with the remainderconsisting of Ni and unavoidable impurities.
 5. An Ni-based singlecrystal super alloy according to claim 1 having a composition comprising5.8 wt % of Al, 5.6 wt % of Ta, 3.1 wt % of Mo, 5.8 wt % of W, 4.9 wt %of Re, 0.10 wt % of Hf, 2.9 wt % of Cr, 5.8 wt % of Co and 5.0 wt % ofRu in terms of weight ratio, with the remainder consisting of Ni andunavoidable impurities.
 6. An Ni-based single crystal super alloyaccording to claim 1 having a composition comprising 5.8 wt % of Al, 5.8wt % of Ta, 3.9 wt % of Mo, 5.8 wt % of W, 4.9 wt % of Re, 0.10 wt % ofHf, 2.9 wt % of Cr, 5.8 wt % of Co and 6.0 wt % of Ru in terms of weightratio, with the remainder consisting of Ni and unavoidable impurities.7. An Ni-based single crystal super alloy according to claim 1 furthercomprising 0-2.0 wt % of Ti in terms of weight ratio.
 8. An Ni-basedsingle crystal super alloy according to claim 1 further comprising 0-4.0wt % of Nb in terms of weight ratio.
 9. An Ni-based single crystal superalloy according to claim 1 further comprising at least one of elementsselected from B, C, Si, Y, La, Ce, V and Zr.
 10. An Ni-based singlecrystal super alloy according to claim 9 having a composition comprising0.05 wt % or less of B, 0.15 wt % or less of C, 0.1 wt % or less of Si,0.1 wt % or less of Y, 0.1 wt % or less of La, 0.1 wt % or less of Ce, 1wt % or less of V and 0.1 wt % or less of Zr in terms of weight ratio.11. An Ni-based single crystal super alloy according to claim 1 having acomposition comprising 5.0-7.0 wt % of Al, 4.0-10.0 wt % of Ta, 1.1-4.5wt % of Mo, 4.0-10.0 wt % of W, 3.1-8.0 wt % of Re, 0-0.50 wt % of Hf,2.0-5.0 wt % of Cr, 0-9.9 wt % of Co, 10.0-14.0 wt % of Ru, 4.0 wt % orless of Nb, 2.0 wt % or less of Ti, 0.05 wt % or less of B, 0.15 wt % orless of C, 0.1 wt % or less of Si, 0.1 wt % or less of Y, 0.1 wt % orless of La, 0.1 wt % or less of Ce, 1 wt % or less of V and 0.1 wt % orless of Zr.
 12. An Ni-based single crystal super alloy according toclaim 1 having a composition comprising 5.8-7.0 wt % of Al, 4.0-5.6 wt %of Ta, 3.3-4.5 wt % of Mo, 4.0-10.0 wt % of W, 3.1-8.0 wt % of Re,0-0.50 wt % of Hf, 2.9-4.3 wt % of Cr, 0-9.9 wt % of Co, 4.1-14.0 wt %of Ru, 4.0 wt % or less of Nb, 2.0 wt % or less of Ti, 0.05 wt % or lessof B, 0.15 wt % or less of C, 0.1 wt % or less of Si, 0.1 wt % or lessof Y, 0.1 wt % or less of La, 0.1 wt % or less of Ce, 1 wt % or less ofV and 0.1 wt % or less of Zr.
 13. An Ni-based single crystal super alloyaccording to claim 1 having a composition comprising 5.0-7.0 wt % of Al,4.0-10.0 wt % of Ta, 1.1-4.5 wt % of Mo, 4.0-10.0 wt % of W, 3.1-8.0 wt% of Re, 0-0.50 wt % of Hf, 2.9-5.0 wt % of Cr, 0-9.9 wt % of Co,6.5-14.0 wt % of Ru, 4.0 wt % or less of Nb, 2.0 wt % or less of Ti,0.05 wt % or less of B, 0.15 wt % or less of C, 0.1 wt % or less of Si,0.1 wt % or less of Y, 0.1 wt % or less of La, 0.1 wt % or less of Ce, 1wt % or less of V and 0.1 wt % or less of Zr.
 14. An Ni-based singlecrystal super alloy according to claim 1 having a composition comprising5.0-7.0 wt % of Al, 4.0-6.0 wt % of Ta, 3.3-4.5 wt % of Mo, 4.0-10.0 wt% of W, 3.1-8.0 wt % of Re, 0-0.50 wt % of Hf, 2.0-5.0 wt % of Cr, 0-9.9wt % of Co, 4.1-14.0 wt % of Ru, 4.0 wt % or less of Nb, 2.0 wt % orless of Ti, 0.05 wt % or less of B, 0.15 wt % or less of C, 0.1 wt % orless of Si, 0.1 wt % or less of Y, 0.1 wt % or less of La, 0.1 wt % orless of Ce, 1 wt % or less of V and 0.1 wt % or less of Zr.
 15. AnNi-based single crystal super alloy according to claim 1 having acomposition comprising 5.0-7.0 wt % of Al, 4.0-5.6 wt % of Ta, 3.3-4.5wt % of Mo, 4.0-10.0 wt % of W, 3.1-8.0 wt % of Re, 0-0.50 wt % of Hf,2.0-5.0 wt % of Cr, 0-9.9 wt % of Co, 4.1-14.0 wt % of Ru, 4.0 wt % orless of Nb, 2.0 wt % or less of Ti, 0.05 wt % or less of B, 0.15 wt % orless of C, 0.1 wt % or less of Si, 0.1 wt % or less of Y, 0.1 wt % orless of La, 0.1 wt % or less of Ce, 1 wt % or less of V and 0.1 wt % orless of Zr.
 16. An Ni-based single crystal super alloy according toclaim 1 having a composition comprising 5.0-7.0 wt % of Al, 4.0-10.0 wt% of Ta, 3.1-4.5 wt % of Mo, 4.0-10.0 wt % of W, 3.1-8.0 wt % of Re,0-0.50 wt % of Hf, 2.0-5.0 wt % of Cr, 0-9.9 wt % of Co, 4.1-14.0 wt %of Ru, 4.0 wt % or less of Nb, 2.0 wt % or less of Ti, 0.05 wt % or lessof B, 0.15 wt % or less of C, 0.1 wt % or less of Si, 0.1 wt % or lessof Y, 0.1 wt % or less of La, 0.1 wt % or less of Ce, 1 wt % or less ofV and 0.1 wt % or less of Zr.
 17. An Ni-based single crystal super alloyaccording to claim 1 having a composition comprising 5.8-7.0 wt % of Al,4.0-10.0 wt % of Ta, 3.1-4.5 wt % of Mo, 4.0-10.0 wt % of W, 3.1-8.0 wt% of Re, 0-0.50 wt % of Hf, 2.0-5.0 wt % of Cr, 0-9.9 wt % of Co,4.1-14.0 wt % of Ru, 4.0 wt % or less of Nb, 2.0 wt % or less of Ti,0.05 wt % or less of B, 0.15 wt % or less of C, 0.1 wt % or less of Si,0.1 wt % or less of Y, 0.1 wt % or less of La, 0.1 wt % or less of Ce, 1wt % or less of V and 0.1 wt % or less of Zr.
 18. An Ni-based singlecrystal super alloy according to claim 1 having a composition comprising5.0-7.0 wt % of Al, 4.0-10.0 wt % of Ta, 3.1-4.5 wt % of Mo, 4.0-10.0 wt% of W, 3.1-8.0 wt % of Re, 0-0.50 wt % of Hf, 2.9-4.3 wt % of Cr, 0-9.9wt % of Co, 4.1-14.0 wt % of Ru, 4.0 wt % or less of Nb, 2.0 wt % orless of Ti, 0.05 wt % or less of B, 0.15 wt % or less of C, 0.1 wt % orless of Si, 0.1 wt % or less of Y, 0.1 wt % or less of La, 0.1 wt % orless of Ce, 1 wt % or less of V and 0.1 wt % or less of Zr.
 19. AnNi-based single crystal super alloy according to claim 1 having acomposition comprising 5.0-7.0 wt % of Al, 4.0-10.0 wt % of Ta+Nb+Ti,3.3-4.5 wt % of Mo, 4.0-10.0 wt % of W, 3.1-8.0 wt % of Re, 0-0.50 wt %of Hf, 2.0-5.0 wt % of Cr, 0-9.9 wt % of Co, 4.1-14.0 wt % of Ru, 0.05wt % or less of B, 0.15 wt % or less of C, 0.1 wt % or less of Si, 0.1wt % or less of Y, 0.1 wt % or less of La, 0.1 wt % or less of Ce, 1 wt% or less of V and 0.1 wt % or less of Zr.
 20. An Ni-based singlecrystal super alloy according to claim 1 wherein, when lattice constantof matrix is taken to be a1 and lattice constant of precipitation phaseis taken to be a2, a2≦0.999a1.
 21. An Ni-based single crystal superalloy according to claim 20 wherein the lattice constant of theprecipitation phase a2 is 0.9965 or less of the lattice constant of thematrix a1.
 22. An Ni-based single crystal super alloy, wherein latticeconstant of its precipitation phase a2 is 0.9965 or less of latticeconstant of its matrix a1, and having a composition including Re and Ru,and 2.9-4.5 wt % of Mo.
 23. An Ni-based single crystal super alloy,wherein lattice constant of its precipitation phase a2 is 0.9965 or lessof lattice constant of its matrix a1, and having a composition including2.9-4.5 wt % of Mo, 3.1-8.0 wt % of Re and 4.1-14.0 wt % of Ru.
 24. AnNi-based single crystal super alloy according to claim 1 wherein adislocation space of the alloy is 40 nm or less.